Fluid control system for aerial tower



Dec. 10, 1968 L. MYERS 3,415,021

FLUID CONTROL SYSTEM FOR AERIAL TOWER Filed se i. 13, 1967 2Sheets-Sheet 1 FIGJ 4 F'ie.2 40

' INVENTOR.

Lesrer L.Mver-s,

BY M WMDM Dec. 10, 1968 1.. 1.. MYERS 3,415,021

FLUID CONTROL SYSTEM FOR AERIAL TOWER Filed Sept. 13' 1967 2Sheets-Sheet 2 \i Pie 5 96 /oo--- u 90 no 104 n j; INVENTOR. v

Lesrer L. MVers, BY W ,W,\DM

' A T -rornevs.

United States Patent 3 415 021 FLUID CONTROL SYS TEll i FGR AERIAL TQWERLester L. Myers, Fort Wayne, Ind, assignor to Mobile Aerial Towers,Inc., Fort Wayne, Ind, a corporation of Indiana Filed Sept. 13, 1967,Ser. No. 667,545 9 Claims. (Cl. 52--115) ABSTRACT OF THE DISCLOSURE Astop valve for a fluid motor provided to raise and lower the boom of anaerial tower, the stop valve comprising means defining a passage throughwhich fluid flows to the motor, a member arranged alternatively to blockthe passage and to permit flow of fluid therethrough, and means defininga chamber in which the member freely moves between its blocking positionand its position permitting flow of fluid through the passage, thechamber being arranged for movement corresponding to the boom movementso that, when the boom approaches its rest position, the stop valve isoperated to deenergize the motor.

Background of the invention Field of the inventi0n.-The presentinvention relates to aerial towers, and more particularly to theprovision of a stop valve for a fluid motor arranged to raise and lowera boom of an aerial tower. The stop valve is arranged to deenergize thefluid motor when the boom approaches its rest position, thereby torelieve the fluid pressure on the motor when the boom is supported inits rest position.

Description of the prior art.--Mobile aerial towers of the so-calledcherry picker type are well known and conventionally comprise a mobileplatform or truck upon which a tower structure is mounted forthree-dimensional operation. The tower structure conventionally includesa pedestal mounted on the truck and a rotatable platform mounted on thepedestal. An elongated lower boom is pivotally mounted on the rotatableplatform at one end for swinging movement about a horizontal axis. Tothe other end of the lower boom is pivotally connected an upper boom forswinging movement about a horizontal axis. To the remaining, outer endof the upper boom is pivotally connected a personnel bucket which is atall times maintained in a level position regardless of the position andelevation to which the two booms may be moved. Suitable motors areconnected to the rotatable platform and to the booms, respectively, bywhich rotary motion of the platform as well as relative swingingmovement of the booms may be obtained. The booms are swingable to alower position in which the personnel bucket is adjacent to the truckand to an elevated position of a desired height above the truck withinthe limits of the boom dimensions.

Such aerial tower structures are shown in the Lester L. Myers PatentsNos. 3,169,602, issued Feb. 16, 1965; 3,231,044, issued Jan. 25, 1966;and 3,233,700, issued Feb. 8, 1966.

The lower boom of such aerial towers is supported in its rest positionby a frame or saddle carried on the truck. Conventionally, adouble-acting piston and cylinder arrangement is provided to pivot theboom on the platform, the piston rod of such arrangement being pivotallyconnected to the platform and the opposite end of the cylinder beingpivotally connected to the boom. In the past, fluid under pressure hasbeen applied to the cylinder until the boom is supported in its restposition on the abovementioned saddle. Since no means has been providedfor conveniently relieving the fluid pressure in the cylinder "ice afterthe boom is lowered into its saddle, the boom is strongly urged againstthe saddle. In some instances, this urging of the boom against thesaddle has resulted in sub stantial damage to the tower mechanism. It isthe purpose of the present invention to relieve this forceful engagementof the boom with the saddle.

Summary of the invention The present invention comprises a stop valvefor a fluid motor provided to raise and lower the lower boom of anaerial tower, the stop valve comprising means defining a passage throughwhich fluid flows to the motor, a member arranged alternatively to blockthe passage and permit flow of fluid therethrough, and means defining achamber in which the member freely moves between its blocking positionand its position permitting flow of fluid through the passage, thechamber being arranged for movement when the boom moves so that when theboom approaches its rest position, the stop valve is operated todeenergize the motor. In the preferred embodiment of the presentinvention, the blocking member is a ball and the means defining achamber is an elongated rectilinear tube in which the ball is free toroll under the influence of gravity, one end of the tube correspondingto the blocking position of the ball. This tube, which preferably iscarried on the fluid motor, is arranged that when the boom approachesits rest position, the ball will roll to its blocking position, therebyto deenergize the fluid motor.

It is therefore an object of the present invention to provide a stopvalve arranged to relieve the fluid pressure on a fluid motor used toposition a boom when the boom is engaged with and supported by supportmeans, thereby to prevent damage resulting from the urging of the boomagainst the support means.

Another object of the present invention is to provide such a stop valvecomprising means defining a passage through which fluid flows to thefluid motor, a member arranged alternatively to block said passage andto permit the flow of fluid therethrough, and means defining a chamberin which said member freely moves between its blocking position and itsposition which permits the flow of fluid through the passage, thechamber being movable when the boom moves so that the member is actedupon by gravity.

Brief description of the drawings The above-mentioned and other featuresand objects of this invention and the manner of attaining them willbecome more apparent and the invention itself will be best understood byreference to the following description of an embodiment of the inventiontaken in conjunction with the accompanying drawings, wherein:

FIG. 1 is an elevational view, not necessarily to scale, showing themain elements of an aerial tower embodying the stop valve of the presentinvention;

FIG. 2 is a view showing the fluid motor used to pivot the lower boom ofthe aerial tower and the manner in which fluid is supplied to the fluidmotor;

FIG. 3 is an enlarged elevation view of the stop valve shown connectedto the fluid motor in FIG. 2;

FIG. 4 is a sectional view taken from FIG. 3 generally along the line44; and

FIG. 5 is a sectional view of another stop valve which may be used tocontrol the fluid motor of FIG. 2.

Description of the preferred embodiment Referring to the drawings, andmore particularly t FIG. 1 a frame 10, which may be the chassis of atruck is shown as having a supporting pedestal 12 mounte thereon, whichpedestal carries a platform 14 for rotatio about a vertical axis.Pivotally mounted on platfom 1 is an elongated, lower boom 16, thepivotal connection be tween platform 14 and boom 15 being provided by ahorizontally extending pin or shaft 18. A fluid motor, generallyindicated by reference numeral 19, is provided for pivoting boom 16about the axis of the shaft 18. In the illustrative embodiment, thefluid motor 19 comprises a power cylinder 20 having one of its endspivot ally connected to boom 16 at 22 and its associated piston rod 23pivotally connected to platform 14 at 24. As is conventional, the pistonrod 23, which penetrates one end of cylinder 20, is connected to apiston 26 arranged for reciprocation in cylinder 20.

As shown clearly in FIG. 2, cylinder 20 is provided with an inputfitting 28 at one of its ends and another input fitting 30 at the otherof its ends. Specifically, piston 26 is arranged to reciprocate betweenthe fittings 28 and 30 in response to the pressure of fluid providedthrough these fittings.

As indicated in FIG. 1, a pressurized fluid source 32, which may be ahydraulic pump, is provided for energizing the power cylinder 20, thesource 32 being connected to the fitting 28 through a conduit 34, avalve indicated by reference numeral 36 and another conduit 38, and tothe fitting 30 by a conduit 40, the valve 36, another conduit 42 and astop valve, indicated generally by reference numeral 44.

Pivotally connected to the outermost end of the lower boom 16 is anelongated upper boom 46, the pivotal connection between these two boomsbeing provided by means of a suitable pin or shaft 48 passing throughthe respective ends of these booms. This pin or shaft 48 has its axisarranged horizontally such that the two booms 16 and 46 may berelatively moved in a common vertical plane. A conventional personnelbucket 50 is pivotally mounted on the distal end of upper boom 46.Suitable controls, not shown, are provided for adjusting the position ofplatform 14 on the pedestal 12, the position of boom 16 relative toplatform 14 and the position of boom 46 relative to boom 16. Of course,a suitable motor, not shown, must be provided for moving boom 46relative to boom 16.

When the aerial tower illustrated in FIG. 1 is not being used, boom 16is pivoted in the direction of the arrow 52 to its rest position and theupper boom 46 is pivoted in the direction of the arrow 54 to its restposition. When boom 16 is in its rest position, the distal end of boom16 is supported on a saddle-like support 56 mounted on frame 10. Therest positions of booms 16 and 46 are shown by the dashed-line drawingsof portions of the booms in FIG. 1.

It will be apparent, therefore, that in order to move the boom 16 towardits rest position on support 56, fluid must be provided through theinput fitting 30 to move cylinder 20 in the direction of arrow 58relative to piston 26, thereby to pivot the boom 16 in the direction ofarrow 52. Likewise, in order to raise boom 16 from its position onsupport 56, fluid must be provided to cylinder 20 through the inputfitting 28 to move the cylinder in a direction opposite to arrow 58.

The valve 36 is a conventional means for regulating the flow of fluidthrough two conduits, and since it is conventional, it need not bediscussed in detail in this description. Specifically, the valve 36 isarranged that when fluid is permitted to flow into one of the inputfittings 28, 30, fluid is permitted to leave the other fitting 28, 30.For example, when valve 36 is in one control position, fluid may flowfrom the source 32 through conduit 34, valve 36 and conduit 38 to thefitting 28 while fluid is flowing from cylinder 20 through the fitting30, conduit 42, valve 36 and conduit 40 back to the source 32.

The stop valve 44 is preferably arranged that when boom 16 issubstantially horizontal and ready to engage support 56, the flow offluid from conduit 42 into fitting 30 will be stopped, and boom 16 willbe permitted to gravitate slightly to its rest position on the support56.

Referring now to FIGS. 3 and 4, the structure of the illustrative stopvalve 44 will be discussed.

The stop valve 44 comprises an elbow fitting 60 having an externallythreaded portion 62 and an internally threaded portion 64, the axes ofportions 62 and 64 forming an angle of approximately 135. A passage 66coaxially arranged in portion 62 is in communication with the openingdefined by the internally threaded portion 64. An adapter 68 having athreaded, counterbore 70 therein is soldered, brazed, or otherwisesecured to fitting 60 as indicated at 72. The adapter 68 is alsoprovided with a passage 74 which is aligned with a passage 76 formed inthe side of fitting 60 to be in communication with passage 66 and thespace defined by the internally threaded portion 64. Thus, fluid canflow into the counterbore 70, through passages 74 and 76 and out ofpassage 66. Preferably, portion 62 is threaded into input fitting 30 ofthe cylinder 20, and conduit 42 is connected to counterbore 70.

Referring to FIG. 4, it will be seen that fitting 60 is formed toprovide a radially outwardly and peripherally extending shoulder 78about the upper portion of passage 66, the shoulder 78 providing a valveseat as will be discussed in the following paragraphs.

The stop valve 44 further comprises a tube 80, one end of which is openand the opposite end of which is closed. The open end of tube 80 isthreadedly received in the internally threaded portion 64 as shown inFIG. 4. A ball 82 is rollably carried in the internal diameter of tube80 so that when the tube 80 is inclined as shown in FIG. 4, ball 82 willbe against the seat provided by shoulder 78 to close the passage 66. Ofcourse, when the closed end of tube 80 is lower than the open end of thetube, the ball 82 will move to the position suggested by the dashed-linedrawing of the ball 82 (FIG. 4) and the passage 66 will be incommunication with passages 74 and 76. Thus, by positioning stop valve44 on the power cylinder 20 as shown in FIG. 1, fluid flow to thecylinder through input fitting 30 is stopped when tube 80 is pivoted inthe direction of arrow 84 (FIG. 1) until the open end of the tube isjust slightly lower than the closed end of the tube. Preferably, ball 82will block the flow of fluid through passage 66 just before the distalend of boom 16 engages support 56.

The length of tube 80 is critical because if the tube is too short, theball 82 will close permaturely when fluid flow is desired. In oneembodiment of the present invention, the tube 80 may be approximatelyfour inches long and the internal diameter of the tube may beapproximately of an inch.

Referring now to FIG. 5, another embodiment of a stop valve will bediscussed. The stop valve of FIG. 5, indicated generally by referencenumeral 86, comprises a fitting 88 defining a passage 89 through whichfluid may flow, a ball 90 arranged alternatively to block the passage ofthe fitting 88 and to permit the flow of fluid through said passage, anda tube 92, similar to tube 80, in which the ball 90 may freely rollbetween its position blocking the passage of the fitting 88 and itsposition which permits the flow of fluid through the passage 89. As seenin FIG. 5, the passage 89 through the fitting 88 is defined by aninternally threaded opening 94, a bore 96 at the lower end of theopening 94, a threaded opening 98 into which the tube 92 is threaded, abore 100 which is concentric with the axis of the tube 92 and a bore 102which is concentrically arranged in an externally threaded portion 104.There is a radially outwardly and peripherally extending shoulder 106about the bore 100 providing a valve seat for the ball 90 when the ballis blocking the flow of fluid through the fitting 88. A street elbow 108is connected to the threaded portion 104 to provide a means forselecting the desired inclination of the tube 92.

The stop valve 86 may be connected to the power cyl inder 20 bythreading the end 110 of the elbow 108 into the input fitting 30 andconnecting the conduit 42 to 5 the threaded opening 94. The inclinationof the tube 92 is selected by rotating the fitting 88 relative to theelbow 108.

While there have been discussed above the principles of this inventionin conjunction with specific apparatus, it is to be clearly understoodthat this description is made by way of example and not as a limitationto the scope of the invention.

What is claimed is:

1. An apparatus of the character described comprising platform means, aboom having opposite ends, one end of said boom being connected to saidplatform means for pivotal movement about a generally horizontal axis,means for supporting the other end of said boom in a rest position, afluid motor arranged to pivot said boom about said horizontal axis,conduit means for connecting said fluid motor to a pressurized fluidsource, and valve means arranged to control the flow of fluid throughsaid conduit means, thereby to energize and deenergize said fluid motor,said valve means comprising means defining a passage through which fluidflows, a member arranged alternatively to block said passage and topermit flow of fluid therethrough, and means defining a chamber in whichsaid member freely moves between its blocking position and its positionwhich permits flow of fluid through said passage, said chamber beingarranged for movement corresponding to the movement of said boom sothat, when the other end of said boom approaches said support means,said valve means is operated to deenergize. said fluid motor.

2. An apparatus as in claim 1 wherein said member is a ball and whereinsaid means defining a chamber is an elongated rectilinear tube in whichsaid ball is free to roll under the influence of gravity, one end ofsaid tube corresponding to said blocking position.

3. An apparatus as in claim 2 wherein said tube is carried on said fluidmotor so that, when said boom is in its said rest position, said tube isinclined so that said one end of said tube is lower than its oppositeend.

4. An apparatus as in claim 1 wherein said fluid motor comprises a powercylinder having fluid inputs at each end, a piston arranged forreciprocation in said cylinder, and a piston rod connected to saidpiston and penetrating one end of said cylinder, said piston rod beingpivotally connected to said platform means and said cylinder beingpivotally connected to said boom, said passage being in communicationwith said input adjacent the end of said cylinder penetrated by saidpiston rod, and said member being arranged to block said passage whenthe other end of said boom approaches its said rest position.

5. An apparatus as in claim 4 wherein said means defining a passage is afitting connected to said input, wherein said means defining a chamberis an elongated rectilinear tube mounted on said fitting, and whereinsaid member is a ball free to roll from end to end in said tube, saidfitting having an aperture therein defining a portion of said passage,and one end of said tube being positioned so that said ball may closesaid aperture.

6. An apparatus of the character described comprising a pivotallymounted fluid motor, conduit means for connecting said fluid motor to apressurized fluid source, and valve means arranged to control the flowof fluid through said conduit means, thereby to energize and deenergizesaid fluid motor, said valve means comprising means defining a passagethrough which fluid flows, a member arranged alternatively to block saidpassage and to permit flow of fluid therethrough, and means defining achamber in which said member .freely moves between its blocking positionand its position which permits fiow of fluid through said passage, saidchamber being mounted for movement corresponding to the pivotal movementof said fluid motor so that, when said fluid motor approaches apredetermined position, said valve means is operated to deener gize saidfluid motor.

7. An apparatus as in claim 6 wherein said member is a ball and whereinsaid means defining a chamber is an elongated rectilinear tube in whichsaid ball is free to roll under the influence of gravity, one end ofsaid tube corresponding to said blocking position.

8. A stop valve comprising a fitting defining a passage through whichfluid flows, said fitting having an aperture therein defining a portionof said passage, a member arranged alternatively to open and close saidaperture, an elongated chamber having first and second ends, said memberbeing freely movable in said chamber between said first and second ends,said chamber being arranged relative to said fitting so that, when saidmember is at said first end, said aperture is closed, and so that, whensaid first end is moved to a position lower than said second end, saidmember will gravitate to said first end, thereby to close said apertureto block the flow of fluid through said passage.

9. A stop valve as in claim 8 wherein said member is a ball, and whereinsaid fitting is formed with a peripherally and laterally extendingshoulder about said aperture to provide a valve seat for said ball.

References Cited UNITED STATES PATENTS 2,946,339 7/1960 Fairchild et al13738 2,949,741 8/1960 Troche et al. 60-97 3,190,391 6/1965 Hoard 182--23,233,700 2/1966 Myers 1822 HENRY C. SUTHERLAND, Primary Examiner. P. C.FAW, JR., Assistant Examiner.

US. Cl. X.R.

